neqn(1) neqn(1)
NAME
neqn, checkeq  Typesets mathematical equations and expressions
SYNOPSIS
neqn [dxy] [pn] [sn] [fn] [file...]  nroff...
checkeq [file...]
DESCRIPTION
The neqn command is an nroff(1) preprocessor for displaying mathematical
symbols and equations on terminals. Usage almost always involves prepro
cessing an nroff source file with neqn and then piping the output through
nroff.
Note
The neqn command formatting works best on typesetting devices. Your
terminal might not be equipped to display equations and other math
symbols in a meaningful way. In fact, you might have difficulty view
ing the symbols and examples included in this reference page.
If no files are specified, neqn reads from the standard input. A line
beginning with .EQ marks the start of an equation; .EN at the beginning of
a line marks the end of an equation. Neither of these lines is altered, so
they can be defined in macro packages to produce centering, numbering, and
so on.
It is also possible to set two characters as delimiters; subsequent text
between delimiters is also treated as input to neqn. Delimiters may be set
to any two characters, such as x and y, with the commandline argument dxy
or more commonly by placing delim xy between .EQ and .EN. The left and
right delimiters can be identical. Delimiters are turned off by delim off.
All text that is neither between delimiters nor between .EQ and .EN is
passed through untouched.
The program checkeq reports missing or unbalanced delimiters and .EQ/.EN
pairs.
Tokens within neqn are separated by spaces, tabs, newlines, braces, double
quotation marks, tildes, or circumflexes. Braces { } are used for grouping.
Generally speaking, anywhere a single character could appear, a complicated
construction enclosed in braces can be used instead. The tilde (~)
represents a full space in the output; the circumflex (^) half as much.
Subscripts and superscripts are produced with the keywords sub and sup.
Fractions use the keyword over.
The sqrt keyword creates square roots.
The keywords from and to are used to express lower and upper limits.
Left and right brackets, braces, and so forth that encompass more than one
line are created with the left and right keywords and tildes. Legal char
acters to use with left and right are {, }, [, ], , c (ceiling), f
(floor), and , meaning `nothing' (to use with the left keyword when you
want brackets or braces on the right side only). The right keyword clause
is optional.
Vertical piles of things are made with pile, lpile, rpile, and cpile.
There can be an arbitrary number of elements in a pile. You use lpile to
leftjustify a vertical grouping and rpile to rightjustify one. The pile
and cpile keywords create centered piles but have different vertical spac
ing.
You use the matrix keyword to create matrixes. The lcol, ccol, and col
keywords are used with matrix to specify the alignment within the matrix;
that is a leftjustified column, centered column, and rightjustified
column, respectively.
Diacritical marks are made with the following keywords:
dot
Produces a period (.) over the character preceding the
keyword.
dotdot
Produces two periods (..) over the character preceding the
keyword.
hat
Produces a circumflex (^) over the character preceding the
keyword.
tilde
Produces a tilde (~) over the character preceding the key
word.
bar
Produces a horizontal bar over the character preceding the
keyword.
vec
Produces a leftpointing arrow over the character preced
ing the keyword.
dyad
Produces a bidirectional arrow over the character preced
ing the keyword.
under
Produces an underscore under the character preceding the
keyword.
Size and font changes are made with the following keywords:
Specifies the size as n points.
size n
size+n Increases the size n points.
sizen Decreases the size n points.
roman Uses roman type font.
italic Uses italic type font.
bold Uses bold type font.
Uses the specified type font.
font n
Size and font can be changed globally in a document by using the gsize n
and the gfont n keyword expressions or by the commandline arguments s n
and f n.
Normally subscripts and superscripts are reduced by three point sizes from
the previous size. You can change this default with the p n commandline
argument.
To aline successive display arguments, place the mark keyword before the
desired lineup point in the first equation. Then place the lineup keyword
at the place that is to line up vertically in subsequent equation lines.
New keywords or new forms of existing keywords can be defined with the
define keyword. For example, the following define expression defines the
new keyword cc to be C Language:
define cc % C Language %
Whenever cc appears in the source file, processing with neqn causes C
Language to appear in the preprocessed or output file. Note that the delim
iting character surrounding the replacement string can be any character as
long as it does not appear in the replacement string itself.
The following keywords are also recognized for typeset output:
sum Produces a large Greek sigma indicating summation.
int Produces an integration sign.
inf Produces an infinity sign.
>>= Produces a greaterthanorequals sign.
<<= Produces a lessthanorequals sign.
>> Produces a right pointing arrow.
<< Produces a left pointing arrow.
!= Produces a not equal sign.
Greek letters are spelled out in the desired case, for example, alpha or
GAMMA. Mathematical words like sin, cos, log are output in roman type
automatically. Strings enclosed in double quotation marks ("...") are
passed through untouched; this feature permits keywords to be entered as
text.
RESTRICTIONS
To embolden digits, parentheses, and so on, you must enclose them in quota
tion marks after the keyword bold. For example:
bold "12.3".
EXAMPLES
1. Input and output for x with subscript i:
x sub i > x
i
2. Input and output for x with subscript i and superscript 2:
x sub i sup 2 > x2
i
3. Input and output for e with a superscript of x squared plus y squared:
2 2
x +y
e sup {x sup 2 + y sup 2} > e
4. Input and output for the fraction q over r:
q
q over r > _
r
5. Input and output for the fraction of 1 over the square root of a poly
nomial that includes a superscript:
1
1 over sqrt {as sup 2 +bx+c} > _________
2
\ax +bx+c
6. Input and output for an expression with a lower and upper limit:
n
lim from {n> inf } sum from 0 to n x sub i > lim Rxi
n>oo0
7. Input and output for an expression with large left and right braces:
{ 2 y }
_2
left {x sup 2 = y sup 2 over alpha right} ~=~ 1 > {x +A } = 1
{ }
8. Input and output for a "pile" expression:
a
pile { a above b above c } > b
c
9. Input and output for an expression with a matrix:
matrix {lcol { x sub i above y sub 2 } ccol { 1 above 2 }} >
x 1
i
y 2
2
SEE ALSO
nroff(1), tbl(1), ms(5)
